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Dunilite – Rare Olivine

Dunilite - Rare Olivine group Gemstones from danugroup.lkv

Dunilite is a rare olivine group mineral with the corresponding chemical formula Magnesium, Iron, Manganese, Silicate (Mg,Fe,Mn)2SiO4. Long mistaken for green peridot, dunilite was identified in 2000 as a new gem variety from the olivine group. Dunilite- Discovered by Mr. Dunil Palitha Gunasekera in 1996.

Dunil Palitha Gunasekera Dip. Gem, FGA,- President Crystals Gallery -Gem Lab

Dunilite occurs in only one locality called, “Katukubura mountain” Kolonne, Sri Lanka. Dunilite can be found in colours light greenish-yellow to brownish green, the depth of colour being related to the iron content of the stone.

Group: Olivine
Crystal System: Orthorhombic
Lustre: Vitreous
Fluorescence: None
Hardness: 6 1/2
Fracture: Uneven
Cleavage: None
Specific Gravity: 3.48
Optic Sign: Biaxial (-)
Dispersion: 0.020
Transparency: Transparent to translucent
Habit: Tabular, rectangle shaped aggregate crystals.

Refractive Index: a= 1.677, B=1.700, y=1.718 ( The refractive indices of dunilite are higher than peridot and sinhalite )

Similarly looks with Faceted Stones:Yellow chrysoberyl, Sinhalite
Might be confused with:Peridot, Forsterite, Sinhalite
Birefringence : 0.041
Radioactivity:Not Radioactive
Dispersion:Relatively Weak
Pleochroism:Strong : Brownish Yellow/ Greenish Yellow
Usual Sizes:0.05 to 1 carat
Occurrence:In a huge calcite rock with black amphibole rocks

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